Significant Increase In Epidermal Thickness Research Articles

Variations in epidermal thickness in expanded human breast skin.

Tissue expansion generates metabolic and morphological changes in the expanded tissues. The alteration of epidermal and dermal thickness has been investigated in many animal studies, but few human studies have been published. We have studied 11 women whose breasts were reconstructed with tissue expansion after mastectomy. The expanded breast skin was biopsied on three occasions: before expansion, at the time of maximal expansion, and six months after the completed reconstruction. Specimens were prepared for light microscopy and epidermal thickness was assessed. There was a significant increase in epidermal thickness (p < 0.05) at the time of maximal expansion. The values before and at six months after reconstruction were not significantly different from each other. We conclude that the epidermis increases in thickness as a result of expansion and returns to normal thickness six months after cessation of expansion.

Topical Retinaldehyde on Human Skin: Biologic Effects and Tolerance

The present study was designed to explore if *etinaldehyde, a natural metabolite of vitamin A, has any biologic activity and is tolerated by human skin. Biologic activity was shown by the induction of cellular retinoic acid-binding protein type 2 (CRABP 2) mRNA and protein; the rank order for CRABP-2 increase was retinoic acid > retinaldehyde > 9 cis retinoic acid > retinol > beta carotene. In volunteers treated 1-3 months with 0.5, 0.1, and 0.05% retinaldehyde, there was a dose-dependent and significant increase in epidermal thickness, keratin 14 immunoreactivity, and Ki67-positive cells. The area of distribution of involucrin, transglutaminase, and filaggrin immunoreactivity was also increased in a dose-dependent manner, and keratin 4 immunoreactivity was induced in the upper epidermis. In pilot clinical tolerance studies, 229 patients received topical retinaldehyde at different concentrations; the 1% preparation was tolerated by up to 70% of the treated subjects; tolerance of the 0.5% preparation was slightly better, whereas both 0.1 and 0.05% preparations applied on facial skin were well tolerated and allowed prolonged use (up to 3 years) in patients with inflammatory dermatoses. These findings indicate that topical retinaldehyde has biologic activity and is well tolerated on human skin.

UV-induced alterations in skin and lymphocytes during a one-week holiday in the Canary Islands in May.

The effect of solar exposure during a one-week sunbathing vacation in May at 29 degrees N latitude was investigated in 22 volunteers. The following end-points were measured before and after the holiday: skin reflectance at 507 nm, transmission of radiation from 289 nm to 448 nm through the epidermis, epidermal thickness, minimal erythema dose (MED), total white cell, neutrophil, lymphocyte, and lymphocyte subpopulation counts in blood, spontaneous DNA synthesis, DNA strand breaks and sister-chromatid exchange in lymphocytes, and the UVC tolerance of lymphocytes. There was a statistically significant decrease in skin reflectance (p < 0.001) and epidermal transmission (p < 0.01) after the holiday, reflecting increased pigmentation and epidermal thickening. There was a statistically significant increase in epidermal thickness (p < 0.001), MED (p < 0.05), spontaneous DNA synthesis (p < 0.01) and DNA strand breaks in lymphocytes (p < 0.02) after the holiday. The other end-points were not significantly changed. We report that changes in skin pigmentation and epidermal thickness occur after one week of UV exposure. It was also observed that a one-week UV exposure increased both spontaneous DNA repair and the amount of DNA strand breaks in the lymphocytes of the volunteers, while no changes in T-cell subsets were detected.

Endocrine factors affecting cell replacement and cell loss in the epidermis and sebaceous glands of the female albino rat.

SUMMARY 1. Hypophysectomy and adrenalectomy in female albino rats aged 9 months were followed by an enlargement of the sebaceous glands and a thickening of the stratum germinativum plus stratum granulosum in the skin of the back. In similar rats aged 5 months hypophysectomy produced a very significant increase in epidermal thickness, but the increase in the mean volume of the sebaceous glands was not statistically significant. 2. In rats aged 5 months hypophysectomy appeared to increase the incidence of mitoses in both tissues, as measured 5 hr after the injection of colchicine. In rats aged 9 months these increases were less marked in the sebaceous glands and insignificant in the stratum germinativum. 3. Implantation of oestradiol/cholesterol for 3–4 weeks caused a marked reduction in size of the sebaceous glands in intact, in hypophysectomized, and in adrenalectomized rats. Epidermal thickness remained unaffected in intact adult rats, but was reduced in hypophysectomized or adrenalectomized rats. 4. The incidence of mitoses in the sebaceous glands and stratum germinativum was not affected 3–4 weeks after the implantation of oestradiol in intact, in hypophysectomized, and in adrenalectomized rats. 5. Spaying had no significant effect on sebaceous gland size, epidermal thickness, or incidence of mitoses. 6. The following main conclusions are suggested by the results: (a) The normal breakdown of sebaceous cells, epidermal keratinization and subsequent cell loss in the skin of the back of the rat are delayed by interference with the pituitary-adrenal system. (b) Oestradiol accelerates the breakdown processes even in the absence of the pituitary and adrenal glands. (c) In the adult female rat mitosis in the epidermis and sebaceous glands neither requires nor is greatly affected by the presence of oestradiol. (d) In the absence of the pituitary the incidence of mitoses in the epidermis and sebaceous glands may be increased; it is possible therefore that a pituitary or adrenal hormone may inhibit mitosis.